Guest guest Posted December 4, 2007 Report Share Posted December 4, 2007 > > Val thinks I may have a problem with RT3, where can I go to read up Some info from my files: Small amounts of rT3 are made within the thyroid; however, peripheral generation from T4 is estimated to account for 95 percent of all rT3 produced.[5] The enzyme responsible for this conversion is 5- deiodinase and is not believed to be dependent on selenium for its activity. This enzyme acts on the nonphenolic ring of T4 (the inner tyrosyl ring) to produce the hormonally inactive rT3. Under normal conditions, 45-50 percent of the daily production of T4 is transformed into rT3. Substantial individual variation in these percentages can be found secondary to a range of environmental, lifestyle, and physiological influences. Causes of decreased T3 and increased rT3: Aging [12] Burns/thermal injury[63] Caloric restriction and fasting[64-66] Chemical exposure[67] Cold exposure[68] Chronic alcohol intake[69] Free radical load[30] Hemorrhagic shock[70] Insulin-dependent diabetes mellitus[71] Liver disease[31] Kidney disease[72,73] Severe or systemic illness[74] Severe injury[76] Stress[77] Surgery[15,78-80] Toxic metal exposure[26-29] Changes in 5'-deiodination occur in a number of situations, such as stress, poor nutrition, illness, selenium deficiency, and drag therapy. Toxic metals such as cadmium, mercury, and lead, have been associated with impaired hepatic 5'-deiodination in animal models.[26- 29] Results suggest free radicals are also involved in inhibition of 5'-monodeiodinase activity; Drugs that increase RT3: Drug (use/class) rT3 Dexamethasone (corticosteroid)[81] increase Propylthiouracil (thiourylene)[82] increase Iopanic acid (radiographic contrast agent)[83] increase Sodium Ipodate (radiographic contrast agent)[84] increase Amiodarone (antiarrhythmic/antianginal)[85] increase Propranalol (beta blocker)[86] increase Elevations in cortisol,[13,14] catecholamines,[15] and some cytokines (IL-6, TNF-[Alpha], and IFN-[Alpha]),[18-20] and low serum albumin levels[12] have been associated with low T3 syndrome. It has been suggested that high levels of cortisol might be responsible for the altered T4 peripheral metabolism to T3 and rT3 in these patients.[76] Soy protein consumption also was found to contribute to age-related alterations in thyroid hormone in animals.[132] These alterations included a decline in T4, fT4, T3, and 2,3'-T2 and an increase in rT3. [132] Because of its role as a cofactor for type I 5'-deiodinase, selenium's influence on deiodination is the best characterized of any nutrient. While a selenium deficiency does not seem to result in a decrease in the production of T4 or T3 within the thyroid gland, deficiency substantially alters the conversion of T4 to T3 in peripheral tissues such as the liver and kidney. This is generally accompanied by reduced T3 and an increased rT3 in the circulation. Zinc deficiency appears to strongly inhibit type I 5'-deiodinase in animal models; however, the mechanism for this effect is not understood and it is currently not clear if a similar role for zinc exists in humans. A little long, I know, but probably beneficial reading for quite a few here. Barb Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 4, 2007 Report Share Posted December 4, 2007 http://www.google.com/search?client=firefox-a & rls=org.mozilla%3Aen-US%3Aofficial\ & channel=s & hl=en & q=%22reverse+T3%22 & btnG=Google+Search -- Artistic Grooming- Hurricane WV http://www.stopthethyroidmadness.com/ http://health.groups.yahoo.com/group/NaturalThyroidHormonesADRENALS/ Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 4, 2007 Report Share Posted December 4, 2007 Great! Do you have a link to the original paper? I'm saving this info! sol Barb wrote: > Some info from my files: > Small amounts of rT3 are made within the thyroid; however, peripheral > generation from T4 is estimated to account for 95 percent of all rT3 > produced.[5] The enzyme responsible for this conversion is 5- > deiodinase and is not believed to be dependent on selenium for its ........................ Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 4, 2007 Report Share Posted December 4, 2007 > > Great! Do you have a link to the original paper? > I'm saving this info! > sol > http://findarticles.com/p/articles/mi_m0FDN/is_4_5/ai_65068470/pg_1 Excellent reading for all you insomniacs! Barb Quote Link to comment Share on other sites More sharing options...
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